| 摘要 |
PURPOSE:To obtain an integrated circuit having a desired function by changing the characteritics of a plurality of bi-polar transistors combined in an integrated circuit by varying the depth of the base region of each transistor. CONSTITUTION:On the surface of a P type semiconductor substrate 1, N<+> type buried layers 2a and 2b, N type semiconductor layers 3a and 3b to be collector regions, P<+> type semiconductor separating layers 4a-4c and P type semiconductor layers 5a and 5b to be base regions are formed by the ordinary method. Then only the surface of the P type semiconductor layer 5b of the NPN transistor needing a high hFE is selectively etched. By varying the etching amount, the depth of the P type semiconductor layer 5b to be base region is changed to control the value of hFE. Said procedure permits an integrated circuit including bi-polar transistors of different characteristics to be readily prepared. |
